A Light-Emitting Diode (LED), as used herein, is a semiconductor light source for generating light at a specified wavelength or a range of wavelengths. LEDs are traditionally used for indicator lamps, and are increasingly used for displays and general lighting. An LED emits light when a voltage is applied across a p-n junction formed by oppositely doping semiconductor compound layers. Different wavelengths of light can be generated using different materials by varying the bandgaps of the semiconductor layers and by fabricating an active layer within the p-n junction. Additionally, an optional phosphor material changes the properties of light generated by the LED.
Continued development in LEDs has resulted in light that can cover the visible spectrum and be used as a lighting source. These attributes, coupled with the potentially long service life of solid state devices, enabled a variety of new applications such as replacement lamps to compete with the well entrenched incandescent and fluorescent lamps for general lighting